I have a 12 lunchbox, and I had an 18, that I upgraded to a 20 with shelix (powermatic209hh), Get the biggest you can afford. I like it for what others have said you can have a wide top go through and, for me, even with a shelix, if if get some squirely figured wood i can run it through canted (pass through at an angle) to the side to make it easier to get through.

Just my 2cw